Identifying Hybridisation in Pinus Species Using near Infrared Spectroscopy of Foliage

Abstract

Near infrared (NIR) spectra from foliage of the tropical pine species Pinus caribaea var. hondurensis, P. elliottii var. elliottii and their hybrids have been used to classify the extent of hybridisation for the F1 and backcross progeny. Comparison of results for F1 hybrids with simulated hybrids, made from admixtures of pure parent foliage samples, showed increased variation in the NIR spectra of the F1 hybrids as evidenced by greater scatter in the principal component analysis scores plot. Both partial least-squares–discriminant analysis and soft independent modelling of class analogy using the foliage spectra provide identification of the hybrid individuals from the parent taxa. In addition, it is possible to visualise the extent of genetic additive effect in hybrid-parent backcrosses. NIR spectra from foliage samples of P. radiata, a temperate pine species, were clearly discriminated from P. elliottii and P. caribaea. Near infrared spectroscopy has the potential to confirm and assess the extent of hybridisation in softwood species. In extreme situations whereby trial records are lost or trial plot labelling is missing, it might be possible to use NIR spectra from foliage to recover taxon information of seedlings.